PNI Flashcards
Define the direct connection between CNS and immune system.
- neuronal
- innervation of primary and secondary lymphoid organs (PVN)
- innervation of adrenal medulla (splanchnic)
Define the indirect connection between CNS and immune system.
- neuroendocrine
- via neurohomormones
Describe the activation process of the neuroendocrine connection.
- Physical or psychological stressor causes release of ACh, GABA, catecholamines, or serotonin
- These activating factors stimulate the PVN of the hypothalamus to release CRH
- CRH goes to the anterior pituitary to stimulate release of ACTH
- ACTH activates adrenal cortex to release cortisol
- cortisol has an inhibitory effect on immune cells
Describe the activation process of the neuronal connection.
- peripheral nerves directly innervate primary and secondary lymphoid organs
- sympathetic splanchnic nerves innervate the adrenal medulla to release catecholamines
- catecholamines, ACh, and neuropeptides directly bind to immune cells (lymphocytes, neutrophils, mononuclear cells, and NK cells)
Bone marrow is stimulated by..?
noradrenergic fibers (norepinephrine)
Thymus is stimulated by…?
- noradrenergic
- cholinergic
- peptidergic
Spleen is stimulated by…?
- noradrenergic
Lymph nodes are stimulated by…?
- noradrenergic
- peptidergic
All primary and secondary lymphoid organs respond to…?
norepinephrine
Which immune cells respond to catecholamines, ACh, and neuropeptides?
- T and B lymphocytes
- mononuclear cells
- NK cells
- neutrophils
What is the effect of cortisol on immune cells?
- anti-inflammatory
- reduces inflammatory cytokine production
- reduces T and B cell reactivity
- reduces NK cell activity
What is the effect of catecholamines on immune cells?
- leukocyte mobilization
- increased NK cell activity
What is the effect of endorphins on immune cells?
- made from POMC and split into ACTH and endorphins when CRH is released
- analgesia
- increase T and NK cell reactivity
- act like hormones
What is the effect of enkephalins on immune cells?
- analgesia
- released from brain, pituitary, and adrenal medulla
- increase T and NK cell reactivity
- act like neurotransmitters
Describe the physiological effect of acute controllable stress.
- increased HR
- increased catecholamines
- increased cortisol
- increased number of circulating leukocytes
- increased NK cells and activity
What is the main cause of increased NK cell activity during acute stress?
catecholamines
What happens 1 hour after an acute stress?
- normalization of circulating leukocytes
- leukocytes have localized to their regional lymph nodes
- allows you to fight off infection and wounds that may have occurred during the “fight or flight” response
- due to catecholamines and cortisol
What is the reason for lymphocyte localization after an acute stressor?
- cortisol
- catecholamines
- adhesion molecule modification (increased expression of CD11a, increased expression of ICAM on endothelial cells
Describe the effect of cortisol on delayed type 4 hypersensitivity (DHT) responses.
- small doses = increased response
- large doses = decreased response
- chronic doses = decreased response
- acute doses = increased response
===> chronic stress depresses the immune system
What are physiological markers of chronic stress (from taking care of an ill patient)?
- decreased cytokine production (IL-1, IL-2)
- decreased antibody production
- increased frequency of colds
Which cytokines can have an effect on the CNS?
- IL-1
- IL-6
- TNFa
What effect do cytokines have on the CNS?
- change firing frequency => influence secretion of HPA axis (ACTH)
Which cells can produce neurotransmitters/neuropeptides? Which neurotransmitters do they produce?
- T and B cells
=> ACTH
=> beta-endorphins
=> enkephalins
What effect do endorphins and enkephalins secreted by immune cells have?
analgesia at site of infection
